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Chapter 8 - Clayton State University
Chapter 8 - Clayton State University

...  Standard molar enthalpies of elements in their most stable forms at 298.15 K and 1.000 atm are zero.  Example: The standard molar enthalpy of formation for phosphoric acid is -1281 kJ/mol. Write the equation for the reaction for which Horxn = -1281 kJ. ...
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... will reduce aldehydes, ketones, esters, carboxylic acid chlorides, carboxylic acids and even carboxylate salts to alcohols. Amides and nitriles are reduced to amines. In each case the partially negative hydrogen reacts with the partially positive carbon of the substrate. It can also be used to reduc ...
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HL ISSN: 2231 – 3087(print) / 2230 – 9632 (Online)

... room temperature. The Mannich base was then acetylated by refluxing it with acetic anhydride for about 24 hrs and the volatile material was distilled out under reduced pressure to give crude diacetate. It is not purified further and directly treated with conc. Hydrochloric acid to gives 2hydroxy-5-f ...
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Woodward–Hoffmann rules



The Woodward–Hoffmann rules, devised by Robert Burns Woodward and Roald Hoffmann, are a set of rules in organic chemistry predicting the barrier heights of pericyclic reactions based upon conservation of orbital symmetry. The Woodward–Hoffmann rules can be applied to understand electrocyclic reactions, cycloadditions (including cheletropic reactions), sigmatropic reactions, and group transfer reactions. Reactions are classified as allowed if the electronic barrier is low, and forbidden if the barrier is high. Forbidden reactions can still take place but require significantly more energy.The Woodward–Hoffmann rules were first formulated to explain the striking stereospecificity of electrocyclic reactions under thermal and photochemical control. Thermolysis of the substituted cyclobutene trans-1,2,3,4-tetramethylcyclobutene (1) gave only one diastereomer, the (E,E)-3,4-dimethyl-2,4-hexadiene (2) as shown below; the (Z,Z) and the (E,Z) diastereomers were not detected in the reaction. Similarly, thermolysis of cis-1,2,3,4-tetramethylcyclobutene (3) gave only the (E,Z) diastereomer (4).Due to their elegance and simplicity, the Woodward–Hoffmann rules are credited with first exemplifying the power of molecular orbital theory to experimental chemists. Hoffmann was awarded the 1981 Nobel Prize in Chemistry for this work, shared with Kenichi Fukui who developed a similar model using frontier molecular orbital (FMO) theory; because Woodward had died two years before, he was not eligible to win what would have been his second Nobel Prize for Chemistry.
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